PENDRED-SYNDROME - 100 YEARS OF UNDERASCERTAINMENT

Pendred syndrome is an autosomal recessive condition classically chara cterized by deafness and goitre. Since both cochlear and thyroid patho logy are required to secure the diagnosis, it is unclear whether the c ondition might present without the classical features. The perchlorate discharge test, the gold-standard investigation for Pendred syndrome, is non-specific. and in the absence of alternative means of confirmin g the diagnosis, its sensitivity is unknown. We used the recent mappin g of the gene to chromosome 7q to identify pedigrees with a likely dia gnosis of Pendred syndrome, and assessed the prevalence of clinical pa rameters of disease in affected patients. Thirty-six familial cases sh owed co-segregation between disease and the Pendred syndrome locus on chromosome 7q. Clinical and investigative findings were compared in in dex cases (n = 18) vs. affected siblings (n = 18). The overall prevale nce of goitre was 73%, higher in index cases (94%) than in siblings (5 6%), many of whom had not previously been considered to have the condi tion. One perchlorate discharge test was false-negative (2.9%). Radiol ogical malformations of the cochlea were identified in 86% of cases. S ecuring a diagnosis of Pendred syndrome may be difficult, especially i n the single case. The perchlorate discharge test, although valuable, is difficult to undertake in the younger patient, and radiology may as sist in diagnosing such patients.